The present invention relates to a coating method and apparatus for a semiconductor process, and, in particular, to a method and apparatus for coating a target substrate, such as a semiconductor wafer or an LCD substrate, with a coating liquid, such as a photo-resist liquid or a developing liquid. The semiconductor process includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having, for example, wiring layers and electrodes to be connected to a semiconductor device on a target substrate, such as a semiconductor wafer or an LCD substrate, by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
In a process of manufacturing a semiconductor device or an LCD, coating apparatuses are utilized in various steps. A representative one of them is a coating apparatus of a photo-resist liquid, employed in a coating and developing system of the photo-resist. The photo-resist liquid is applied onto a target layer to be pattern-etched, such as a semiconductor, insulating, or conductive layer on a semiconductor, so as to form a photo-resist film on the target layer. The photo-resist film is exposed to light through a predetermined mask and is developed so that the film is patterned to copy the mask. Then, the target layer is etched, using the patterned photo-resist film as a mask.
Jpn. Pat. Appln. KOKAI Publication Nos. 7-8879, 7-8880, 7-8034, 7-80385, and 7-80386, and Jpn. U.M. Appln. KOKAI Publication No. 7-31168 disclose a coating method of a certain type for applying a photo-resist liquid. In this coating method, a target substrate and a nozzle for delivering the photo-resist liquid in a band shape are moved relative to each other in a direction perpendicular to the band of the photo-resist liquid, so that the top surface of the target substrate is coated overall with the photo-resist liquid.
However, this method entails the following problems. First, since a solvent contained in the photo-resist liquid is evaporated while the liquid is applied onto the target substrate from its one end to the other, there is a difficulty in forming a thin film, and the necessary amount of the photo-resist liquid is relatively large. Further, as shown in FIG. 8, more photo-resist liquid is applied at the start and end points of the coating process, thereby bringing about a difficulty in forming a film having a uniform thickness. Furthermore, the surface of the target substrate occasionally has a bad wettability relative to the photo-resist, depending on the properties of the surface, thereby bringing about difficulties in forming a film having a uniform thickness and in performing a process with a small amount of the photo-resist liquid.